Kinetic energy recovery systems for motor vehicles which convert kinetic energy of the motor vehicle into electrical energy which is stored in a battery or a high power capacitor can save energy. Likewise, systems that store rotational energy in a flywheel can also save energy. The energy which is stored in this way can subsequently be converted into torque for the purpose of vehicle propulsion in order to assist an internal combustion engine of a motor vehicle. A disadvantage of such systems is that there may be low conversion efficiency back and forth between the energy system components.
Under certain circumstances it may be advantageous to save kinetic energy in its present form instead of storing it. In the case of internal combustion engines with an automatic transmission there are possible ways of opening the drivetrain so that braking torques, such as are caused by the engine and possible kinetic energy recovery systems, are reduced. This leads to a condition in which the vehicle is decelerated to a lesser degree and therefore continues to move forward.
The description is based on the object of saving energy in motor vehicles with a manual transmission. The description is set forth with the features of the claims.
The inventors herein have recognized the above-mentioned disadvantages and have developed a method for operating a vehicle drivetrain, comprising: automatically decoupling an engine from vehicle wheels in response to a driver releasing an accelerator pedal, the vehicle drivetrain including a driver operated clutch.
By decoupling an engine from vehicle wheels during conditions where an accelerator is not applied, it may be possible to reduce engine fuel consumption. For example, when a vehicle is coasting without accelerator input, the vehicle may coast farther when the engine is decoupled from the vehicle wheels since the engine does not act to brake the vehicle. Further, the engine can be decoupled from the vehicle wheels differently depending on conditions such as road grade, ambient temperature, and vehicle towing state.
The present description may provide several advantages. Specifically, the approach may reduce engine fuel consumption. Further, the approach may reduce vehicle emissions by allowing an engine to be stopped during vehicle coast conditions (e.g., where the vehicle is moving without torque from an engine) for a longer period of time. Further still, the approach may be useful for teaching a driver fuel saving driving techniques.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.
The drawings included herein serve merely for the explanation of the description, and do not restrict the description. The reference symbols that are common to more than one figure are used to denote identical or similar parts between different figures.